There are plenty of things that can cause fires that are not oxygen, and don't contain oxygen.
The halogens, Fluorine and Chlorine in particular, are powerful oxidizing agents on their own and can produce flames in the same manner as common flames.
Here's a report on the spectra of flames produced by combustion in a Fluorine atmosphere (PDF warning).
Role of thumb is an employee costs roughly twice their base salary, as the employee still needs to cover insurance, taxes, sick time, and other benefits.
That leaves an average salary of 190K for the 50 employees. That isn't much for tech.